In general, a fuel cell is an electricity generating system that generates electric energy through an electrochemical reaction between oxygen and hydrogen or hydrogen contained in hydrocarbon materials such as methanol, ethanol, or natural gas.
A polymer electrolyte membrane fuel cell (hereinafter, referred to as PEMFC) has been developed recently which has excellent output characteristics, low operating temperatures, and fast starting and response characteristics. PEMFCs have a wide range of application including mobile power sources for vehicles, distributed power sources for home or buildings, and small-sized power sources for electronic apparatuses.
A fuel cell system employing the PEMFC scheme basically requires a stack, a reformer, a fuel tank, and a fuel pump. The stack constitutes an electricity generation unit and has a plurality of unit cells and the fuel pump supplies fuel from the fuel tank to the reformer. Then, the reformer reforms the fuel to generate hydrogen and supplies hydrogen to the stack.
The reformer generates hydrogen from the fuel through a catalytic chemical reaction using thermal energy. Therefore, the reformer comprises a heat source unit for generating the thermal energy and a reforming unit for generating hydrogen from the fuel using the thermal energy.
In a conventional reformer of a fuel cell system, since the heat source unit and the reforming unit are formed in a vessel shape and are connected to each other through pipes, the heat is not exchanged directly between the respective reaction units, thereby causing a disadvantage in thermal conduction. In addition, since the respective reaction units are separate, the system cannot be implemented compactly.